Re: GIN logging GIN_SEGMENT_UNMODIFIED actions?

On Tue, Aug 30, 2016 at 3:13 PM, Fujii Masao <masao.fujii@gmail.com> wrote:
> On Tue, Aug 30, 2016 at 3:39 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Fujii Masao <masao.fujii@gmail.com> writes:
>>> ISTM that the cause of this issue is that gin_desc() uses XLogRecGetData() to
>>> extract ginxlogVacuumDataLeafPage data from XLOG_GIN_VACUUM_DATA_LEAF_PAGE
>>> record. Since it's registered by XLogRegisterBufData() in
>>> ginVacuumPostingTreeLeaf(),
>>> XLogRecGetBlockData() should be used, instead. Patch attached. Thought?
>>
>> I think we probably have more issues than that.  See for example
>> https://www.postgresql.org/message-id/flat/20160826072658.15676.7628%40wrigleys.postgresql.org
>>
>> which clearly shows that the replay logic is seeing something wrong too:
>>
>> 2016-08-26 06:01:50 UTC FATAL:  unexpected GIN leaf action: 0
>> 2016-08-26 06:01:50 UTC CONTEXT:  xlog redo Insert item, node:
>> 1663/16387/33108 blkno: 6622 isdata: T isleaf: T 3 segments: 2 (add 0 items)
>> 0 unknown action 0 ???
>>
>> If it were just a matter of gin_desc() being wrong, we'd not have
>> gotten such a failure.  (Which is not to say that gin_desc() isn't
>> wrong; it may well be.)
>
> Yeah, I got the pg_xlogdump issue while I was trying to reproduce
> the above reported problem. Fixing pg_xlogdump would be helpful for
> the analysis of that problem.

Attached is the updated version of the patch.

I found that pg_xlogdump code for XLOG_GIN_INSERT record with
GIN_INSERT_ISLEAF flag has the same issue, i.e.,
"unknown action 0" error is thrown for that record.
The latest patch fixes this.

Regards,

--
Fujii Masao